Effects of feeding system and pre-partum supplementation on the β-carotene status of South African Holstein cows

AbstractThe objectives were to investigate the β-carotene status of dairy cows under various production systems, and determine effect pre-partum supplementation on their post-partum status. Ten farms selected from each three namely pasture-based, hay-based total mixed ration (TMR) silage-based TMR. Twenty per farm sampled in system, blood plasma concentration was determined with a portable spectrophotometer (n = 200 system). Mean concentrations pasture-fed 5.54 mg/L, higher (P <0.05) than (2.98 mg/L) maize TMR systems (1.71 mg/L); status, therefore, these optimal, marginal, deficient, respectively. In second experiment, 10 received control TMR, supplemented 1.2 g/day day -56 calving monitored until 56 postpartum. The optimal calving, minor carry-over days post partum, then declined gradually they needed supplementation. between groups differed weeks two group being marginal deficient onwards. Forage type its content play major role more research is potential storage mobilization cows.